1. Field of the Invention
The present invention relates to an RF power amplifier which is applicable to a portable terminal, such as a portable phone or a portable communication device, and more particularly, to an RF power amplifier which can perform an electrostatic discharge (ESD) protection function, without signal distortion, and can be implemented inexpensively by reducing the number of diodes for ESD protection.
2. Description of the Related Art
In general, a portable terminal, such as a portable phone or a portable communication device, is designed to have a large number of integrated circuits (ICs), including an RF power amplifier, in order to increase the power of a transmit signal.
In order for a more reliable operation of a portable terminal, ESD protection circuits are necessarily provided in all IC output terminals. In particular, as compared to other circuits, a voltage higher than a power supply voltage is generated at an output terminal of an RF power amplifier. Hence, it is necessary to further increase the size of an ESD protection circuit.
However, when an ESD circuit is installed in an output terminal of a conventional RF power amplifier, a peak voltage of an output signal is significantly high due to RF power amplification. Therefore, in order to prevent the ESD protection circuit from operating at the peak value of the output signal, a large number of diodes connected in series are used inside the ESD protection circuit, thereby increasing the size thereof. The manufacturing costs of the ESD protection circuit are additionally increased.